Question

我正在开发一个Android应用程序，在其中我从URL获取单个图像，然后将其存储到Sq lite数据库中。

目前同样的图像（Abc.png）存储在sq lite数据库中的次数超过一次，当我一次又一次地启动Activity时......我希望那个相同的图像（Abc.png）不能存储多次。< / p>

如果在此之后数据库中没有行，则如何通过将其存储在数据库中来停止相同的图像（Abc.png）。

我怎么能这样做？？

这是我的代码： -

PanoramaViewActivity

public class PanoramaViewActivity extends Activity {

// Set your Image URL into a string
String URL = "http://mw2.google.com/mw-panoramio/photos/medium/17287086.jpg";
ImageView image, imagetop;
ProgressDialog mProgressDialog;

private ImageDbAdapter mDbAdapter;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.panoramaview);

    // Locate the ImageView in activity_main.xml
    image = (ImageView) findViewById(R.id.img);
    imagetop = (ImageView) findViewById(R.id.imgtop);

    // Execute DownloadImage AsyncTask
    new DownloadImage().execute(URL);

}

// DownloadImage AsyncTask
private class DownloadImage extends AsyncTask<String, Void, Bitmap> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Create a progressdialog
        mProgressDialog = new ProgressDialog(PanoramaViewActivity.this);
        // Set progressdialog message
        mProgressDialog.setMessage("Loading...");
        mProgressDialog.setIndeterminate(false);
        // Show progressdialog
        mProgressDialog.show();
    }

    @Override
    protected Bitmap doInBackground(String... URL) {
        String imageURL = URL[0];
        Bitmap bitmap = null;
        try {
            // Download Image from URL
            InputStream input = new java.net.URL(imageURL).openStream();
            // Decode Bitmap
            bitmap = BitmapFactory.decodeStream(input);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bitmap;
    }

    @Override
    protected void onPostExecute(Bitmap result) {
        // Set the bitmap into ImageView
        image.setImageBitmap(result);
        // Close progressdialog
        mProgressDialog.dismiss();

        insertToDB(result);
        queryFromDB();
    }
}

private void insertToDB(Bitmap result1) {
    mDbAdapter = new ImageDbAdapter(this);
    mDbAdapter.open();
    Bitmap photo = result1;
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    photo.compress(Bitmap.CompressFormat.PNG, 100, bos);
    byte[] bArray = bos.toByteArray();
    mDbAdapter.insert(bArray);
}

private void queryFromDB() {
    byte[] image = mDbAdapter.fetchSingle(1);
    imagetop.setImageBitmap(Utilities.getImage(image));
    Log.d("result", "" + mDbAdapter.fetchSingle(1));
    mDbAdapter.close();
}
}

公用事业类： -

public class Utilities {
public static byte[] getBytes(Bitmap bitmap) {
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress(CompressFormat.PNG, 0, stream);
    return stream.toByteArray();
}

public static Bitmap getImage(byte[] image) {
    return BitmapFactory.decodeByteArray(image, 0, image.length);
}
}

ImageDbHelper

public class ImageDbHelper extends SQLiteOpenHelper {

public static final String DB_NAME = "image_storage.db";
public static final int DB_VERSION = 1;

private static final String SQL_CREATE = "CREATE TABLE tbl_image ("
        + "_id INTEGER PRIMARY KEY AUTOINCREMENT, " + "image_data BLOB"
        + ");";

private static final String SQL_DROP = "DROP TABLE IF EXISTS tbl_image;";

public ImageDbHelper(Context c) {
    super(c, DB_NAME, null, DB_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(SQL_CREATE);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL(SQL_DROP);
    onCreate(db);
}

}

ImageDbAdapter

public class ImageDbAdapter {
public static final String TABLE_NAME = "tbl_image";
public static final String COL_ID = "_id";
public static final String COL_DATA = "image_data";

public static final String[] PROJECTION_ALL = new String[] { COL_ID,
        COL_DATA };

private Context mContext;
private SQLiteDatabase mDb;
private ImageDbHelper mDbHelper;

public ImageDbAdapter(Context c) {
    mContext = c;
}

public ImageDbAdapter open() throws SQLException {
    mDbHelper = new ImageDbHelper(mContext);
    mDb = mDbHelper.getWritableDatabase();
    return this;
}

public void close() {
    mDbHelper.close();
}

public long insert(byte[] image) {
    return mDb.insert(TABLE_NAME, null, createContentValues(image));
}

private ContentValues createContentValues(byte[] image) {
    ContentValues cv = new ContentValues();
    cv.put(COL_DATA, image);
    return cv;
}

public byte[] fetchSingle(int id) {
    Cursor queryCursor = mDb.query(TABLE_NAME, PROJECTION_ALL, COL_ID
            + " = " + id, null, null, null, null);
    if (queryCursor == null) {
        return null;
    }
    byte[] image = null;
    if (queryCursor.moveToFirst()) {
        image = queryCursor.getBlob(queryCursor
                .getColumnIndexOrThrow(COL_DATA));
    }
    queryCursor.close();
    return image;
}
}

Answer 1

String URL ="mw2.google.com/mw-panoramio/photos/medium/17287086.jpg"

String[] bits = URL .split("/");

String imagename = bits[bits.length - 1];

System.out.println(imagename);

Result will be  17287086.jpg

相同的图像不能在sqlite中存储多次

1 个答案: